This invention relates to a position detector, for example for detecting the position of a movable object but one example is to detect the vertical position of the tips of rotor blades of a helicopter rotor as they rotate so that any lack of uniformity in the deflection of all the blades in the rotor can be detected and corrected.
Although the invention will be particularly described as applied to that use, it will be appreciated that it can be used for detecting the position of other articles, for example the vertical deflection of the end of a stationary cantilever beam or the deflection of rotor blade tips in a turbine, or components of other rotating machinery.